Trump was initially set to sign the order shortly after his inauguration in January and held a press conference on the issue, but ultimately delayed the signing.

"I think the trend is going in the wrong direction in cyberspace and it's time to stop that trend and reverse it on behalf of the American people," Trump's homeland security adviser Tom Bossert told reporters after the president signed the executive order.

"We've seen increasing attacks from allies, adversaries, primarily nation-states, but also non-nation-state actors, and sitting by and doing nothing is no longer an option," he said.

In the executive order, Trump has directed his Cabinet to begin the "hard work" of protecting most critical infrastructures, utilities, financial and health care systems and telecommunications networks.

"He's directed them to identify additional measures to defend and secure our critical infrastructure. And he's continued to promote the message that doing nothing is no longer an option," Bossert said.

"The executive order not only requires departments and agencies to help those critical infrastructure owners and operators, and the most important ones, but to do it in a proactive sense. The message is a tilt toward action," he said.

Bossert said the first priority for Trump is protecting the federal networks. "We operate those federal networks on behalf of the American people and they often contain the American people's information and data. So not defending them is no longer an option," he explained.

"We've seen past hacks and past efforts that have succeeded, and we need to do everything we can to prevent that from happening in the future," the White House official said adding that Trump in his executive order has directed his departments and agencies to implement the NIST framework, the risk-reduction framework.

"It is something that we have asked the private sector to implement, and not forced upon ourselves. From this point forward, departments and agencies shall practice what we preach and implement that same NIST framework for risk management and risk reduction," he said.

The executive order also directs all departments and agency heads to continue its key roles, but it also centralises risk. "So we view our federal IT as one enterprise network. If we don't do so, we will not be able to adequately understand what risk exists and how to mitigate it," Bossert said.